Today, GaN/AlN nanowires are envisaged as building blocks in several devices such as LEDs. The work presented here is an investigation of the basic properties of those nanowires, as concerns their growth and optical properties. It aims at increasing the rationality of their growth route and use.

Motivated by the existence of inconsistencies in the literature, the self-organized nucleation of GaN nanowires on silicon substrate is re-investigated. Noticeably, the N polarity rather than the underlying micro-structure of the substrate is non-ambiguously evidenced as a requisite for triggering nanowire nucleation.

A side product of the systematic polarity analysis performed on nanowires is the discovery of inversion domains. They are shown to correlate with a specific luminescence at 3.45 eV, which brings a decisive answer to the controversial origin of this photoluminescence line reported for long in nanowires.

The growth of quantum heterostructures in nanowires spontaneously results in disk-like structures having photoluminescence properties deeply linked to the nanowire structure. In order to limit this dependence, the growth of dot-like heterostructures is proposed and their nucleation through a novel growth route is demonstrated.

At last, the measurement of diffusion lengths of charge carriers in GaN and AlN nanowires is used to probe the inner electronic potential landscape of nanowires.